Ibm binary incompatible problem between gcc and xl compilers for vector data types
Generate code that keeps does not keeps some integer operations adjacent so that the instructions can be fused together on power8 and later processors.
Generate code that uses does not use the vector and scalar instructions that were added in version 2. Also enable the use of built-in functions that allow more direct access to the vector instructions.
Generate code that uses does not use the non-atomic quad word memory instructions. The -mquad-memory option requires use of bit mode. Generate code that uses does not use the atomic quad word memory instructions. The -mquad-memory-atomic option requires use of bit mode. If you use the ISA 3. Otherwise, if you do not specify to generate ISA 3. The bit environment sets int, long and pointer to 32 bits and generates code that runs on any PowerPC variant.
The bit environment sets int to 32 bits and long and pointer to 64 bits, and generates code for PowerPC64, as for -mpowerpc The -mfull-toc option is selected by default. However, only 16, entries are available in the TOC. If you receive a linker error message that saying you have overflowed the available TOC space, you can reduce the amount of TOC space used with the -mno-fp-in-toc and -mno-sum-in-toc options. You may specify one or both of these options. If you still run out of space in the TOC even when you specify both of these options, specify -mminimal-toc instead.
You may wish to use this option only on files that contain less frequently-executed code. Specifying -maix64 implies -mpowerpc64 , while -maix32 disables the bit ABI and implies -mno-powerpc GCC defaults to -maix Pass floating-point arguments to prototyped functions beyond the register save area RSA on the stack in addition to argument FPRs. Do not assume that most significant double in bit long double value is properly rounded when comparing values and converting to double.
Use XL symbol names for long double support routines. IBM XL compilers access floating-point arguments that do not fit in the RSA from the stack when a subroutine is compiled without optimization. Because always storing floating-point arguments on the stack is inefficient and rarely needed, this option is not enabled by default and only is necessary when calling subroutines compiled by IBM XL compilers without optimization.
Link an application written to use message passing with special startup code to enable the application to run. The Parallel Environment does not support threads, so the -mpe option and the -pthread option are incompatible.
On bit Darwin, natural alignment is the default, and -malign-power is not supported. Generate code that does not use uses the floating-point register set. Software floating-point emulation is provided if you use the -msoft-float option, and pass the option to GCC when linking.
Generate code for single- or double-precision floating-point operations. Do not generate sqrt and div instructions for hardware floating-point unit. Specify type of floating-point unit. Generate code that uses does not use the load multiple word instructions and the store multiple word instructions. Do not use -mmultiple on little-endian PowerPC systems, since those instructions do not work when the processor is in little-endian mode.
Generate code that uses does not use the load or store instructions that update the base register to the address of the calculated memory location. These instructions are generated by default. If you use -mno-update , there is a small window between the time that the stack pointer is updated and the address of the previous frame is stored, which means code that walks the stack frame across interrupts or signals may get corrupted data.
Generate code that tries to avoid not avoid the use of indexed load or store instructions. These instructions can incur a performance penalty on Power6 processors in certain situations, such as when stepping through large arrays that cross a 16M boundary. This option is enabled by default when targeting Power6 and disabled otherwise. Generate code that uses does not use the floating-point multiply and accumulate instructions.
These instructions are generated by default if hardware floating point is used. Generate code that uses does not use the half-word multiply and multiply-accumulate instructions on the IBM , , and processors. These instructions are generated by default when targeting those processors. This instruction is generated by default when targeting those processors. For example, by default a structure containing nothing but 8 unsigned bit-fields of length 1 is aligned to a 4-byte boundary and has a size of 4 bytes.
By using -mno-bit-align , the structure is aligned to a 1-byte boundary and is 1 byte in size. Generate code that allows does not allow a static executable to be relocated to a different address at run time.
A simple embedded PowerPC system loader should relocate the entire contents of. For this to work, all objects linked together must be compiled with -mrelocatable or -mrelocatable-lib. Like -mrelocatable , -mrelocatable-lib generates a. Objects compiled with -mrelocatable-lib may be linked with objects compiled with any combination of the -mrelocatable options.
The -mlittle-endian option is the same as -mlittle. The -mbig-endian option is the same as -mbig. On Darwin and Mac OS X systems, compile code so that it is not relocatable, but that its external references are relocatable. The resulting code is suitable for applications, but not shared libraries. Treat the register used for PIC addressing as read-only, rather than loading it in the prologue for each function.
The runtime system is responsible for initializing this register with an appropriate value before execution begins. This option controls the priority that is assigned to dispatch-slot restricted instructions during the second scheduling pass. This option controls which dependences are considered costly by the target during instruction scheduling. This option controls which NOP insertion scheme is used during the second scheduling pass. The argument scheme takes one of the following values:.
Insert NOPs to force costly dependent insns into separate groups. Insert exactly as many NOPs as needed to force an insn to a new group, according to the estimated processor grouping. Insert number NOPs to force an insn to a new group. Select the type of traceback table. Extend the current ABI with a particular extension, or remove such extension. This is not likely to work if your system defaults to using IEEE extended-precision long double. If you change the long double type from IEEE extended-precision, the compiler will issue a warning unless you use the -Wno-psabi option.
This is not likely to work if your system defaults to using IBM extended-precision long double. If you change the long double type from IBM extended-precision, the compiler will issue a warning unless you use the -Wno-psabi option. Overriding the default ABI requires special system support and is likely to fail in spectacular ways. Otherwise, the compiler must insert an instruction before every non-prototyped call to set or clear bit 6 of the condition code register CR to indicate whether floating-point values are passed in the floating-point registers in case the function takes variable arguments.
With -mprototype , only calls to prototyped variable argument functions set or clear the bit. On embedded PowerPC systems, assume that the startup module is called sim-crt0. On embedded PowerPC systems, assume that the startup module is called crt0. Selecting -mno-eabi means that the stack is aligned to a byte boundary, no EABI initialization function is called from main , and the -msdata option only uses r13 to point to a single small data area.
Put small initialized non- const global and static data in the. Put small uninitialized global and static data in the. Put small uninitialized global data in the. Do not use register r13 to address small data however. This is the default behavior unless other -msdata options are used.
The language was widely adopted by scientists for writing numerically intensive programs, which encouraged compiler writers to produce compilers that could generate faster and more efficient code. The inclusion of a complex number data type in the language made Fortran especially suited to technical applications such as electrical engineering.
For these reasons, FORTRAN is considered to be the first widely used programming language supported across a variety of computer architectures. The main enhancement was to support procedural programming by allowing user-written subroutines and functions. Six new statements were introduced:.
This specification, developed by the U. These features would eventually be incorporated into the Fortran 90 standard. The development of a revised standard to succeed FORTRAN 77 would be repeatedly delayed as the standardization process struggled to keep up with rapid changes in computing and programming practice. This major revision added many new features to reflect the significant changes in programming practice that had evolved since the standard:.
Fortran 95 was a minor revision, mostly to resolve some outstanding issues from the Fortran 90 standard. Nevertheless, Fortran 95 also added a number of extensions, notably from the High Performance Fortran specification:. In addition, aliasing is not an issue for optimization of array references, allowing compilers to generate faster code than in the case of pointers.
This specification defined support for IEEE floating-point arithmetic and floating point exception handling. The most recent standard, Fortran , is a major revision introducing many new features.
Efforts are underway to develop a revision to Fortran , tentatively called Fortran As with Fortran 95, this is intended to be a minor upgrade, incorporating clarifications and corrections to Fortran , as well as introducing a select few new capabilities. Proposed new capabilities include. A full list is in the report "The language features that have been chosen for Fortran " PDF file.
Since Fortran has been around for nearly fifty years, there is a vast body of Fortran in daily use throughout the scientific and engineering communities.
It is the primary language for some of the most intensive supercomputing tasks, such as weather and climate modeling , computational fluid dynamics , computational chemistry , quantum chromodynamics , simulations of long-term solar system dynamics , high-fidelity evolution artificial satellite orbits , and simulation of automobile crash dynamics.
Indeed, one finds that even today, half a century later, floating-point benchmarks to gauge the performance of new computer processors are still written in Fortran e. The Fortran language features described are intended to be a fairly comprehensive overview of the Fortran language; full details may be found in any of several Fortran textbooks. Only those features widely used in new programs are described, as few of the historic features are used in modern programs.
Still, most have been retained in the language to maintain backward compatibility. Portability was a problem in the early days because there was no agreed standard—not even IBM's reference manual—and computer companies vied to differentiate their offerings from others by providing incompatible features.
Standards have improved portability. The standard provided a reference syntax and semantics, but vendors continued to provide incompatible extensions. Government were required to diagnose extensions of the standard. Rather than offer two processors, essentially every compiler eventually had at least an option to diagnose extensions.
Incompatible extensions were not the only portability problem. For numerical calculations, it is important to take account of the characteristics of the arithmetic. This was addressed by Fox et. The ideas therein became widely used, and were eventually incorporated into the standard by way of intrinsic inquiry functions. The widespread now almost universal adoption of the IEEE standard for binary floating-point arithmetic has essentially removed this problem.
Access to the computing environment e. Large collections of "library" software that could be described as being loosely-related to engineering and scientific calculations, such as graphics libraries, have been written in C, and therefore access to them presented a portability problem.